Chapter 5, Problem 1MC

Animal cells are surrounded by________ fluid is ________ fluid. This to the cytosol.

1. a. phospholipid; isotonic
2. b. plasma; hypertonic
3. c. interstitial; isotonic
4. d. interstitial; hypotonic

Summary Introduction

Introduction:

The cytosol is a concentrated aqueous gel inside the plasma membrane. It is composed of many small and large components. Cytosol is made up of fine filaments and intracellular structures called organelles. Cytosol and organelles together, form the cytoplasm.

Answer to Problem 1MC

Correct answer:

Animal cells are surrounded by interstitial fluid. This fluid is isotonic to the cytosol. Therefore, option (c) is correct.

Option (c) is given as “interstitial; isotonic”.

Explanation of Solution

Justify reasons for the correct statement:

The animal cells are enclosed by interstitial fluid that is isotonic to the cytosol. The interstitial fluid is a watery medium in a cell, also known as extracellular fluid. The cytoplasm is separated from the interstitial fluid by the plasma membrane.

Hence, option (c) is correct.

Justify reasons for the incorrect statements:

Option (a) is given as “phospholipid; isotonic”.

The phospholipids are major components of the plasma membrane. Phospholipids are a type of lipid made up of fatty acids, phosphate group, and a glycerol molecule. Hence, it is a wrong answer.

Option (b) is given as “plasma; hypertonic”.

Cell membrane is composed of plasma that is a bilayer of phospholipids. Plasma membrane is isotonic. Hence, it is a wrong answer.

Option (d) is given as “interstitial; hypotonic”.

The animal cells are enclosed by interstitial fluid which is isotonic to the cytosol. Hence, it is a wrong answer.

Hence, options (a), (b), and (d) are incorrect.

Conclusion

Thus, interstitial fluid surrounding the animal cells is isotonic and is also known as extracellular fluid.